X-ray spot filmer wherein the grid is carried by the cassette tray



E. SLAGLE July 21 1970 WHEREIN THE GRID IS HE CASSETTE TRAY 2 Sheets-Sheet 1 X-RAY SPOT FILMER CARRIED BY T Filed Oct. 9, 1967 INVENTOR.EDWARD SLAGLE BY T0113 Hoffmqnn PISML Heinlte.

ATTORNEYS;

- July 21, 1970 E SSSS LE 3,521,061

X-RAY SPOT FI WHEREIN THE GRID IS l-NVENTOR; EDWARD SLAGLE United StatesPatent 3,521,061 X-RAY SPOT FILMER WHEREIN THE GRID lS CARRIED BY THECASSETTE TRAY Edward Slagle, South Euclid, Ohio, assignor, by mesneassignments, to Picker Corporation, White Plains, N.Y.,

a corporation of New York Filed Oct. 9, 1967, Ser. No. 673,649 lnt. Cl.G01n 23/04; G031) 41/16 US. Cl. 25066 Claims ABSTRACT OF THE DISCLOSUREXray spot filmer for taking medical radiographs which minimizespatient-to-film distance with an X-ray absorbing grid which is carriedby a cassette tray so it is fixed during the radiographing operation andis shifted into position automatically with the X-ray film.

CROSS-REFERENCED PATENTS (1) Pat. 2,872,584, issued Feb. 3, 1959, to R.C. Schiring et al., entitled, X-Ray Apparatus;

(2) Pat. 3,173,008, issued Mar. 9, 1965, to D. M. Barrett et al.entitled, Spot Filmer.

BACKGROUND OF THE INVENTION Field of the invention Medical X-ray tablesare frequently equipped with a device known as a spot filmer. One suchspot filmer is that described and claimed in the Pat. 3,173,008 to D. M.Barrett et al. entitled, Spot Filmer. These spot film de vices arecarried on the tower of an X-ray table such as that described andclaimed in R. C. Schiring et al. Pat. 2,872,584 entitled X-RayApparatus.

With an X-ray table equipped with a spot filmer, an X-ray tube iscarried by the tower and positioned Within the body of the X-ray table.The spot filmer is mounted in the path of an X-ray beam emitted by thetube and is movable toward and away from the table body. A cassette.

carrying X-ray film is carried by the spot filmer and is selectivelypositionable in the path of the X-ray beam for taking X-ray radiographs.

In many modern X-ray mechanisms, an image intensification tube iscarried by the spot filmer and used for conducting what is sometimesreferred to as bright fluoroscopy. That is, the patient is fiuoroscopedby use of an image intensification tube and the output of the imageintensification tube may be (1) viewed optically; (2) reproduced on aclosedcircuit television monitor for viewing; and, (3) photographed by acine camera.

The quality of an X-ray radiograph and the quality of the fluoroscopicimage produced by an image intensifier and associated apparatus, isdependent upon a number of factors. One of the more important factors isthe distance between the film or the image intensifier and the patientor other subject being X-rayed. The closer the film is to the patient,for example, the sharper will be the radiograph. An interrelated factoris the distance between the X-ray tube and the film or imageintensification tube. The energy required to produce a suitableradiograph varies with the square of the distance between the X-raysource and the radiographic film. Thus, not only is the quality of theradiograph a function of the distance between the X-ray tube and thefilm but the amount of exposure of X-ray to which the patient issubjected is proportional to that distance.

Another factor in making a limited patient-to-film distance important isthe amount of information which can be obtained on any given film size.The X-ray beam is essentially pyramidal in shape emanating from a pointsource on the anode of the X-ray tube and collimated by diaphragms to arectangular field. For any given field size, the closer the film is tothe patient the larger the X-ray field size which can be accommodatedand therefore the more information which can be presented on the film.

As the X-ray arts have advanced and accessories have been added to spotfilmers the tube-to-film distance and the patientto-film distance hasusually suffered adversely as a consequence. For example, the additionto spot filmers of such accessories as phototiming attachments andgrids, both oscillating and stationary, for inhibiting the fogging ofthe film due to scatter radiation have increased the patient-to-filmdistance and therefore the patient-to-X-raytube distance.

PRIOR ART It is customary to position a grid between the patient and theradiographic film. The grid is a framework equipped with a series ofusually-parallel bars of lead or other material which is impervious topenetration by X- rays. This has the effect of filtering out socalledscatter radiation deflected by the patient and approaching the film atan angle. Thus, the radiographic exposure is made essentially byprimary, substantially parallel radiation passing directly through thepatient to the grid.

Two types of grids have been employed in the past. One is a so-calledstationary grid which is in a fixed position during radiographing andwhich results in parallel lines or bars being visible on the radiograph.For many purposes these bars are not objectionable and do not interferewith the diagnosing of a patient. At other times, an oscillating grid isused. The oscillating grid is caused to reciprocate back and forthduring the X-ray exposure producing the filtering effect insofar asscatter radiation is concerned, but obviating the appearance of gridbars on the finished radiograph.

With prior art spot. filmers, it has been customary to provideradiographic grids as accessories. Grids added to spot filmers in thepast have resulted in increased patientto-film distance.

Moreover, where both fixed and oscillating grids are provided, it isessential that both be movable from a storage to a use position andreturn so that one may selectively and one at a time use either thefixed grid or the oscillating grid, or neither. Thus, they are not inthe same plane and add to the patient-to-film distance.

The use of fixed grids with image intensification tubes creates anotherproblem. Until very recently and to a large degree to this day, theamount of intensification available with image intensification systemshas prohibited the use of heavy grids during times when so-called brightfiuoroscopy studies are conducted. High-quality radiographs, however,require a relatively heavy grid. Accordingly, a compromise to arelatively light grid to get a good quality bright fiuoroscopy work hasresulted in a poorer quality of radiograph.

In the past, where the grid was positioned selectively in the path ofthe X-ray beam, it was necessary for the operator of the mechanism toposition the grid before taking a radiograph or, in the alternative, toprovide a mechanism for automatically positioning the grid. If the gridis positioned automatically, obviously the spot filmer mechanism is mademore complex. If it is necessary to position it manually, there is theadded problem of po tential human error and resultant failure to obtainthe radiographs desired.

SUMMARY OF THE INVENTION The present invention has overcome all of theabove disadvantages and provided additional advantages as Well. With thepresent invention, a film tray which supports the cassette is equippedwith an aperture in the central portion of the lower part of the tray. Aso-called stationary grid is mounted in that aperture so that it moveswith the film from a storage position to the exposure position.Inherently, when the film is in an exposure position, the grid is alsoin that position.

In addition to the advantage of the grid automatically being positionedwithout any addition of any automatic positioning mechanism, thisconstruction has other advantages. Since the grid is positioned in arecess at the base of the film tray, the presence of the grid has noeffect on the film-to-patient distance.

There are many who believe that one factor which contributes togood-quality radiographs is the distance between a grid and aradiograph. These persons assert that if the grid is as close aspossible to the film better quality radiographs are produced. With thepresent mechanism, the grid is juxtaposed against the film cassette andis therefore as close as possible to the grid.

The explanation advanced by those who assert that the grid should be asclose as possible to the film, for their claim of improved radiographs,is that this minimizes to the greatest possible extent the obtuseness ofan angle of incident radiation exposing the radiographic film. In otherwords, it limits the X-rays which reach the film to those more clearlyapproaching parallel than if the grid were spaced further from the grid.

As indicated above, the construction for the fixed grid of thisinvention adds no space at all. All other accessories are selectivelyadded wtih the purchaser again having the ability to determine whetheror not the adverse effect on the radiograph justifies the addition ofthe accessory.

Accordingly, the object of this invention is to provide a novel andimproved X-ray spot filmer equipped with a stationary grid positionedfor radiography in a novel and improved manner.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective somewhatdiagrammatic view of an X-ray table equipped with a spot filmerembodying this invention;

FIG. 2 is an enlarged perspective view of the spot filmer with the imageintensification tube removed for clarity of illustration and the spotfilmer tray partially through the aperture where the image tube iscustomarily mounted; and,

FIG. 3 is an exploded view of the spot filmer cassette tray and theimproved stationary grid construction of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, anX-ray table is shown generally at 10. The table includes a body 11mounted on a pedestal 12. The body 11 has a top 13 which is shown ashorizontal in FIG. 1. The table body 11 is movable from the positionshown to a position wherein the top 13 is vertical. With a so-called9090 table, the body is tiltable in either direction until the top 13 isin a vertical position.

The table 10 includes the usual tower or mast assembly 14 which ismovable longitudinally and transversely with respect to the table top 13to various positions along the table. The tower 14 carries a spot filmershown generally at 15. The spot filmer 15 is movable reciprocally in theusual manner toward and away from the table top 13.

Referring now to FIG. 2, the spot filmer 15 is of the front loadingtype, having a front load opening shown generally at '16. The filmer isequipped with a cassette eject bar 17 which ejects a cassette from thespot filmer whenever the cassette tray 18 is in a load position. Otherparts of the spot filmer shown include a cassette park and load switch19, a lock switch 20 for a Bucky tray carried in the table, a toggleswitch 21 for a power top on the table and a table tilt switch 22. Apower assist handle 23 is provided as is a button 24 for energizingcompression locks. A density control switch 25 is provided at therearward part of the spot filmer for controlling the density of aphototimed radiographic exposure. The film advance button 27 is providedfor causing the cassette tray to advance to an exposure position. Theusual program selector 30 is provided as are diaphragm controls 31 foradjusting the field size of the X-ray beam. All of the structure thusfar defined is known in the art and may be made in accordance with theteachings of the above-referenced Pat. 3,173,008, entitled Spot Filmer.

The spot filmer as shown in FIG. 1 is equipped with an imageintensification tube 33. For clarity of illustration, the imageintensification tube 33 has been omitted from all figures other thanFIG. 1. The image tube is mounted in a well or recess shown generally at34 so as to be positioned as near the patient as possible.

A cassette tray is shown generally at 40 in FIG. 2. Referring to FIG. 3,the cassette tray includes tray body 41. The tray body 41 includes adownwardly bent sloping portion at 42 for guiding a cassette into thetray on rectilinear insertion of it. Side flanges 43, 44 are alsoprovided for camming the cassette into the tray. A pair of side mountingflanges 45, 46 project outwardly from and form a part of the tray 41.

The tray 41 also has a rearwardly extending mounting flange 47 in thesame plane as the side mounting flanges 45, 46. The mounting flanges 45,47 carry suitable rollers 49 for carrying the cassette in its forwardand rearward movement and for carrying it in its transverse movementthrough the usual radiographic sequences.

Other structure carried by the tray has been omitted for clarity ofillustration since it forms no part of this invention. The otherstructure includes such things as the latching mechanism for holding acassette in the tray, the eject mechanism for ejecting the cassette fromthe tray and lead shielding carried by the tray for radiationabsorption.

The tray body 41 includes a base structure defining a generallyrectangular aperture 50 at the bottom. The aperture 50 is of aperimetrical size equal to the size of the fixed grid 51 which issecured in the tray. The grid 51 has the usual parallel bars 52 whichabsorb scatter radiation emanating from a patient and permit the directradiation to pass through to form a sharp and clear radiograph. The grid51 is also of a thickness equal to the bottom portion of the tray body41. Typically, the tray may be formed from a panel of /s inch thicknessand the grid 51 will also be of inch thickness.

A pair of tray mounting plates 53, 54 are provided at opposite sides ofthe aperture 50. The mounting plates 53, 54 are secured in place as byfasteners 55. In assembly, the grid 51 is lowered into the aperture 50and supported on the plates 53, 54. A suitable bonding agent such as anepoxy resin is then poured at the joints between the grid 51 and thewalls of the aperture 50 and above the plates 53, 54 respectively. Thisbonding agent secures the grid in place by bonding it to the supportingplates 53, 54 and to the tray body 41. Thus, the grid is bonded in placeto become a portion of the base structure of the tray.

Although a preferred embodiment of the invention has been shown anddescribed, it is apparent that many changes and modifications may bemade by one skilled in the art without departing from the true spiritand scope of the invention.

What is claimed is:

1. In an X-ray spot filmer including a housing, a cassette tray movablein the housing from load position to a selected exposure position, andstructure within the housing for moving the tray, the improved trayconstruction comprising:

(a) tray structure defining the perimeter of a cassette space;

(b) said structure defining an aperture beneath the space;

(c) a grid in the aperture, said grid having a plurality of spaced,X-ray absorbing bars; and,

(d) said structure including means securing the grid in the aperture.

2. The device of claim 1 wherein said means securing the grid in theaperture comprises a pair of mounting plates secured to the traystructure and means bonding the grid to the plates.

3. The device of claim 2 wherein the means bonding the grid and platescomprises an epoxy resin.

4. In an X-ray spot filmer including a structure for shifting an X-raycassette supporting tray from storage to exposure positions and return,the improved tray construction comprising:

(a) a base structure defining the base of a cassette receiving space;

(b) said base structure including a grid portion disposed centrally andforming the major portion of said base structure, said grid portionincluding a plurality of spaced, X-ray absorbing bars; and,

(c) marginal members projecting upwardly from said base structure anddefining a plurality of sides of the cassette receiving space whereby toprovide marginal members for locating and maintaining the cassettewithin the tray.

5. In an X-ray spot filmer including structure for shifting an X-raycassette supporting tray from storage to exposure positions and return,the improved tray construction comprising:

(a) a base member defining the base of a cassette receiving space; saidbase member having an enlarged aperture therein such that said basemember comprises relatively narrow marginal portions defining theperimeter of the aperture;

(b) a grid disposed within and substantially filling said aperture, saidgrid having a thickness substantially equal to that of the base member,said grid also having a plurality of spaced, X-ray absorbing bars;

(c) means secured to the base member and to the grid and maintaining thegrid in the aperture; and,

(d) marginal flange members projecting upwardly from said base memberand defining at least three sides of the cassette receiving spacewhereby to provide a front opening for insertion of a cassette into saidtray and marginal members for locating and maintaining the cassettewithin the tray.

FOREIGN PATENTS 640,140 12/1936 Germany.

WILLIAM F. LINDQUIST, Primary Examiner US. Cl. X.R. 25062

